Many connectors of the above-mentioned species are known. As a rule, these connectors are made up of two components, namely an inner contact part and a spring element, the spring element taking the form of a so-called external retention spring, which at least partially surrounds the inner contact part. In order to produce an electrical plug connection, the electrical connector is slipped onto a so-called knife blade, the inner contact part coming into contact with the knife blade. The inner contact part itself is divided up into several regions, namely an attachment part, onto which a bare end of an electrical connector is preferably crimped. In addition, the inner contact part has a center segment, which is preferably formed in the shape of a throat, and on whose throat an attachment element is provided that is designed to fix the inner contact part in position. The inner contact part also has a contact segment possessing a contact part that produces an electrical contact with the diametrically opposed knife blade.
As a rule, the contact parts take the form of contact lamellae. An inner contact part has two or more opposite lamellae, which are situated at a distance from each other, which is less than the thickness of the knife blade. The contact lamellae are forced to spring up by inserting the knife blade. This results in a corresponding deformation, which produces a specific normal force on the contact lamellae and the inserted knife blade at the contact point.
Different specific embodiments of the form of the contact lamellae are also known. First of all, it is provided that contact lamellae be exposed (project outward), so that they may freely spring off of a knife blade in response to being slipped onto it. Another specific embodiment shows a clip that embraces the contact lamellae, the clip resting on the external retention spring. Also known is an exemplary embodiment, in which the contact lamellae are welded to the external retention spring.
When electrical connectors are designed in such a manner that the contact lamellae freely extend inside the external retention spring, the disadvantage is that the so-called normal contact force changes due to, in particular, the relaxation of the contact lamellae material. As a result, an electrical plug connection produced as such is cut off by this relaxation process and may cause, therefore, a corresponding fault.
The further designs of contact lamellae have the disadvantage that the respective, normal contact forces are generated as a function of the remaining contact lamellae. In particular, one of two contact points has a normal contact force that is too high, and one has a normal contact force that is correspondingly low, when the knife blade is tilted, and when vibrational and wobbling motions occur. When the normal contact force is too low, this can lead, in the extreme case, to the disengagement and breakdown of the contact point and, therefore, to the termination of the electrical plug connection. A contact force that is too high can also result in permanent damage to the contact surface (of the knife blade and the contact lamellae), which can lead, in turn, to the failure of the contact point and the electrical plug connection over the service life.
The present construction of electrical connectors of the type mentioned above is designed with a view to attaining a specific force at the contact point during the insertion of the knife blade, without the insertion force causing a certain maximum value to be exceeded during the insertion procedure. The possibilities for designing the shape of the insertion force curve are very limited.